Method of manufacturing toothbrushes with common core

ABSTRACT

A dental implement includes a rigid plastic core handle and an overmold. The overmold may have different exterior configurations for different users with the different configurations altered to anatomically fit the targeted user&#39;s hands and to appeal to the targeted user. The method for manufacturing the dental implement includes forming a plastic core in a first mold, removing the plastic core from the first mold, selecting one of a plurality of second molds, with each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second modes and an overmold formed by another one of the plurality of second molds have different configurations, placing the plastic core into the selected one of the plurality of second molds, forming an overmold about the plastic core by injecting an material into the mold cavity, and removing the plastic core and overmold from the mold cavity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of International Application No. PCT/US11/26652, filed on Mar. 1, 2011, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to manufacturing of dental care implements, and more particularly, to methods of manufacturing toothbrushes having common core and overmolds.

BACKGROUND OF THE INVENTION

Oral care implements, especially toothbrushes, are in use by many people on a daily basis. With such devices, a handle is usually provided to be grasped and manipulated by the user as needed. However, many handles are simply linear or anatomically corrected rods of relatively rigid material which are neither comfortable, nor given to easily manipulation. Further, use of an oral care implement may commonly occur under wet conditions, which can cause the handle to be slippery.

To provide improved control and greater comfort for the user, toothbrushes are being provided with softer elastomeric padding over parts of the toothbrush handle, with exemplary teachings provided in U.S. Pat. Nos. 7,458,125; 7,240,390; and 7,401,377. Examples of soft handle coverings for other oral care implements are taught in U.S. Pat. Nos. 5,501,597; 6,361,317; and 7,226,289.

The problems associated with relatively rigid material handle increase when the toothbrush is electrical or otherwise powered, due to the vibrations caused by the electrically manipulated toothbrush head during use. The control of such toothbrushes becomes more problematic when the electric/powered toothbrush is used by the smaller hands of children.

Accordingly, there is a need for an oral care implement that provides for improved control and greater comfort for the use of the implement regardless of the size of the user's hand.

SUMMARY OF THE INVENTION

One aspect of the preferred embodiments includes a method of manufacturing a dental implement. The dental implement includes a shaft having a plastic core and an overmold. The method includes forming a plastic core in a first mold, removing the plastic core from the first mold, selecting one of a plurality of second molds, with each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second modes and an overmold formed by another one of the plurality of second molds have different configurations, placing the plastic core into the selected one of the plurality of second molds, forming an overmold about the plastic core by injecting a material into the mold cavity of the selected one of the plurality of second molds, and removing the plastic core and overmold from the mold cavity.

Another aspect of the preferred embodiments includes method of manufacturing a dental implement. The dental implement includes a shaft having a plastic core and an overmold. The method includes providing a first plastic core formed from a first mold, selecting a first one of a plurality of second molds, each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second molds and an overmold formed by another one of the plurality of second molds have different configurations, placing the first plastic core into the first one of the plurality of second molds, forming a first overmold about the first plastic core by injecting a material into the mold cavity of the first one of the plurality of second molds, and removing the first plastic core and the first overmold from the mold cavity. The method also includes providing a second plastic core formed from the first mold, selecting a second one of a plurality of second molds, placing the second plastic core into the second one of the plurality of second molds, forming a second overmold about the second plastic core by injecting a material into the mold cavity of the second one of the plurality of second molds, and removing the second plastic core and the second overmold from the mold cavity.

A further aspect of the preferred embodiments includes a dental implement kit. The kit includes a first dental implement with a first plastic core formed of a first mold, and a first overmold formed of a first one of a plurality of second molds, each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second molds and an overmold formed by another one of the plurality of second molds have different configurations. The kit also includes a second dental implement with a second plastic core formed of the first mold, and a second overmold formed of a second one of a plurality of second molds. The first overmold and the second overmold have different configurations.

In certain embodiments, the method also includes chemically blending the injected material with the plastic core, and cooling the overmold with the chemically blended injected material and the plastic core forming a chemical bond therebetween. Within this exemplary aspect, the injected material preferably has a temperature that softens the plastic core for chemically blending the core with the injected material. In a further aspect of the preferred embodiments, the method also includes arranging electrically functional elements within the plastic core, the electrically functional elements including an electrically operated functional unit and an electric supply unit connectable to an energy source for energizing the electrically operated functional unit. In yet another aspect of the preferred embodiments, the dental implement includes a head member and a neck located between the head member and the plastic core, and the method may further include attaching a plurality of bristles to the head member to form a brush head. While not being limited to a particular material, the injected material may be, for example, an elastomer.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a top plan view of an exemplary embodiment of a toothbrush constructed in accordance with the preferred embodiments of the invention;

FIG. 2 is a second top plan view of the toothbrush shown in FIG. 1;

FIG. 3 is a side sectional view taken along line III-III of FIG. 2;

FIG. 4 is a top plan view of another exemplary embodiment of a toothbrush constructed in accordance with the preferred embodiments;

FIG. 5 is a second top plan view of the toothbrush shown in FIG. 4; and

FIG. 6 is a side sectional view taken along line VI-VI of FIG. 5.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Unless otherwise specified, all amounts, quantities, and geometric features expressed herein and elsewhere in the specification should be understood to include substantial approximations of the expressed term. For example, the term “planar” should be understood as including generally or approximately planar configurations.

The figures illustrate an oral care or dental implement in the form of a toothbrush having an improved handle and a head with bristles or other tooth engaging elements. While reference is made to a toothbrush with an improved handle, other oral care implements, such as inter-proximal picks, flossing tools, plaque scrapers, tongue and soft tissue cleansers/massagers, and the like, may use the same handle. It should also be understood that other embodiments may be utilized and that structural and functional modifications may be made without departing from the scope of the present invention.

While not being limited to a particular embodiment, the exemplary aspects of the invention include a toothbrush with a rigid plastic core handle that is chemically bonded to a thermoplastic elastomer overmold during an overmolding process, with the overmold defining a gripping region for a user's hand during use of the toothbrush. The resulting overmold grip may have different exterior shapes for different types of users (e.g., adults, children, boys, girls, men, women) with the different shapes altered to anatomically fit the targeted user's hands. For example, boys and girls may prefer different overmold designs, just as men and women or adults and children may prefer different overmold designs especially configured for the respective sizes, strength and pressure applied by the hands of the respective users.

The preferred embodiments improve the control and comfort of the toothbrush for the user by providing a comfortable elastomeric covering about the handle of the toothbrush sized and shaped for the user's hand. A further benefit is provided when the toothbrush is an electric toothbrush. It is well-known that electric/sonic toothbrushes vibrate during use. This vibration can cause discomfort to a user, especially when the user is holding a rigid handle of the vibrating toothbrush. By providing a comfortable elastomeric grip around the toothbrush handle, and not just selected portions thereof, the elastomeric overmold of the preferred embodiments provides a comfortable and secure grip of the toothbrush while reducing the vibration to the user as the vibration is absorbed by the elastomeric covering. Accordingly, a further benefit of the invention is the reduction of healthcare concerns caused to the hand, wrist and forearm of a user by absorption of the vibrations by the elastomeric overmold and resulting reduction of vibrations to the user's joints.

Referring now to the drawings, FIGS. 1-3 illustrate an exemplary embodiment of a toothbrush 10 constructed in accordance with the invention. The toothbrush 10 includes a core handle 12, a head 14 and a neck region 18 coupled therebetween. The core handle 12, neck region 18 and head 14 may be integrally formed or alternatively formed separately and attached along the neck region 18 located between the head and core handle and coupling the two into a single unit. The head 14 has a base portion 20 having a bristle mounting surface or face 22 from which a plurality of bristles 16 may be attached, preferably via insertion into bores 24 (FIG. 3) distributed in the base portion 20 across the face 22.

The core handle 12 is a generally cylindrical or tubular rigid plastic shaft extending from a shank 46 of the neck region 18 to a bottom 26 of the toothbrush 10 at a distal end thereof. While not being limited to a particular embodiment, the toothbrush 10 is an electrical or sonic toothbrush with a bottom end cap 28 attached to the core handle 12, preferably via a frictional fit. The end cap 28 is removable from the core handle at the bottom 26 thereof to expose a cylindrical channel for an energy source (e.g., battery). The end cap 28 preferably has a planar boundary (e.g., rim, wall, face, surface) 30 that allows the toothbrush 10 to stand upright when placed on a planar horizontal surface.

Referring to FIG. 3, the core handle 12 is shown in tubular form enclosing electrically functioning elements 32 that are arranged within the elongated shaft of the core handle 12 and neck region 18. It is contemplated that the core handle 12 is not limited to a cylindrical or tubular shape. For example, the core handle 12 may be of other appropriate shape, such as a variety of suitable polygons. The electrically functional elements 32 include an electrically operated functional unit 34 (e.g., vibration member including an electric motor 36 coupled to an eccentric member 38), and an electric supply unit 40 of conductive lines 42 connectable between the electric motor 36 and an energy source 44 (e.g., battery, rechargeable battery, connector to electrical outlet). In some embodiments, the electrically functional elements 32 may include one or more piezoelectric elements. In some embodiments, the electrically functional elements 32 may include more or fewer components as desired. In the embodiment as shown, a switch 52 at a front side 54 of the toothbrush 10 is operably connectable to the electrically operated functional unit 34 to connect or interrupt power from the energy source 44 to the electrically operated functional unit 34 based on the position of the switch 52, toward or away from contact with the electric supply unit 40.

The core handle 12 is a hard plastic shaft comprising a rigid polymer material. A rigid polymer material provides strength and durability for portions of the toothbrush 10 or dental instrument that will be subjected to stresses and forces associated with gripping the toothbrush 10 and using the toothbrush 10 for its intended dental purpose. Strength and durability will prevent these portions of the toothbrush 10 from cracking or being deformed under stress.

According to the preferred embodiments, the rigid polymer material may include any rigid thermoplastic material. Suitable rigid thermoplastics include polycarbonates, acrylonitrile butadiene styrene, polyamides, acetals, polysulfones, and polypropylene. The rigid polymer material may also include a rigid chemical cure or thermocure polymer material. Besides providing rigidity, strength, and durability, a chemical cure or thermocure polymer material also provides the advantages of being autoclavable. Exemplary rigid chemical cure or thermocure polymers include epoxies, phenolics, acrylates, urethanes and polyesters.

As can be seen in FIGS. 1-3, the toothbrush 10 includes a thermoplastic elastomer (TPE) overmold grip 50 surrounding the core handle 12 where a person's hand is expected to hold the toothbrush 10 during use. While not being limited to a particular construction, the overmold grip 50 is preferably assembled onto the rigid plastic core handle 12 by placing the core handle 12 in a suitable mold that seals off the toothbrush 10 at the shank 46 and the bottom 26 of the shaft. A suitable TPE material is then injected into a suitably shaped mold cavity as understood by a skilled artisan.

The thermoplastic elastomer overmold grip 50 is chemically bonded to the rigid plastic core handle 12 during the overmolding process that forms the overmold grip 50 about the core handle 12. The elastomer overmold grip 50 and the core handle 12 are chemically bonded during the overmolding process for the elastomer overmold grip 50 by the injection of the elastomer that is hot enough to chemically blend with the material of the core handle 12. In particular, the elastomer is injected at a temperature hot enough to cause an outer wall 48 of the plastic core handle 12 to soften or melt sufficiently for chemical blending of the outer wall with the hot elastomeric material of the injection overmold. As the elastomer cools, the chemical blend remains creating a chemical bond for holding the rigid plastic core handle 12 and the thermoplastic elastomer overmold grip 50 together.

The overmold grip 50 is preferably shaped for comfortable handing by the user of the toothbrush 10. It is understood that the invention is not limited to the shape of the overmold grips 50 and 60 (FIGS. 4-6), but that the overmold grip 50, 60 may be formed in any shape that provides the intended user with a comfortable grip for use during the dental procedure. As such, the overmold grip 50, 60 may be formed by conventional means to a shape targeted towards the general size and shape of a user's hand regardless of the age or gender of the user. In addition, the overmold grip 50, 60 may include various configurations, such as different colors, patterns, designs, motifs, etc. Further, in some embodiments, the mold cavity that molds the overmold grip 50, 60 may be adjustable to produce overmold grip 50, 60 of the various shapes, sizes, colors, patterns, designs, motifs, etc.

FIGS. 4-6 depict a second example of the preferred embodiments with a toothbrush 100 substantially similar to the toothbrush 10 discussed above. In particular, the toothbrush 100 shown in FIGS. 4-6 is identical to the toothbrush 10 shown in FIGS. 1-3 except for the exterior shape of the overmold grip 60. The overmold grip 60 is assembled onto the rigid plastic core handle 12 and chemically bonded to the core handle 12 as discussed above for the overmold grip 50. That is, the core handle 12 is preferably placed in a suitable mold that seals off the toothbrush 100 at the shank 46 and the bottom 26 of the core handle 12 shaft. However, the suitable mold is configured differently to form the overmold grip 60 which is different than the overmold grip 50. In other words, the mold cavity of the mold that forms the overmold grip 60 has a different shape, size, color, pattern, design and/or motif than the mold cavity of the mold that forms the overmold grip 50. Regardless of the configuration of the mold cavity, the elastomer is injected at a temperature hot enough to cause the outer wall 48 of the plastic core handle 12 to soften melt sufficiently for chemical blending of the outer wall and the hot elastomeric material of the injected overmold. The overmold grip 60 is formed in an alternative shape for comfortable handling by a user having a different gender or age than the targeted person or group of the first exemplary toothbrush.

According to the preferred embodiments, either of the toothbrushes 10, 100 is preferably made by the same method. For example, the plastic core handle 12 is molded in a first mold as a shaft that is removed from the first mold subsequent the molding. A second mold used for manufacturing one of the overmold grips overmold grips 50 or 60 is selected from a plurality of the second molds, with each of the plurality of second molds having a different mold cavity such that an overmold (e.g., overmold grip 50) formed by one of the plurality of the second modes and an overmold (e.g., overmold grip 60) formed by another one of the plurality of second molds have different configurations. The plastic core handle 12 is placed into the selected one of the plurality of second molds. Then an overmold (e.g., overmold grip 50 or overmold grip 60) is formed about the plastic core handle 12 by injecting a material into the selected mold cavity, and the plastic core handle 12 and the respective overmold grip (e.g., overmold grip 50, overmold grip 60) is removed from the selected mold cavity.

In certain embodiments, a kit may be provided that include a first dental implement with a first plastic core 12 and a overmold grip 50, and a second dental implement with a second plastic core 12 and a overmold grip 60. In this kit, while the plastic core 12 may be common among the dental implements, the overmold grips 50, 60 may have different configurations.

According to the preferred embodiments, the overmold grip 50, 60 comprises a thermoplastic elastomer (TPE) material. The elastomeric material provides increased comfort and gripability to the handle of the toothbrush/dental instrument that is gripped by the user when using the toothbrush manually. Alternatively, the elastomeric material may include an elastomeric chemical cure or a thermocure polymer material for the added advantage of autoclavability. Examples of thermoplastic elastomers include ethylene-propylene rubber, polyolefin elastomers, and synthetic rubber. Examples of suitable elastomer chemical cure or thermocure polymers include silicon rubber, natural rubber, synthetic rubber, and lower durometer urethanes. To provide optimal comfort as well as control benefits, the elastomeric material of the overmold grip surface preferably has a hardness durometer measurement ranging between A11-A50 Shore hardness, although materials outside this range may be used. A more preferred range of the hardness durometer rating is between A25-A40 Shore hardness.

While the invention has been described in detail and with reference to specific examples thereof, it would be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. For example, the end cap 28 is preferably attached to the core handle 12 by threaded, snap fit or other frictional engagement, yet may alternatively be attached by non-frictional means such as an adhesive or magnets within the scope of the invention. Without further elaboration, the foregoing will so fully illustrate the invention that others may, by applying current or future knowledge; readily adapt the same for use under various conditions for service.

As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. 

1. A method of manufacturing a dental implement, the dental implement having a shaft with a plastic core, and an overmold, the method comprising: a) forming a plastic core in a first mold; b) removing the plastic core from the first mold; c) selecting one of a plurality of second molds, each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second molds and an overmold formed by another one of the plurality of second molds have different configurations; d) placing the plastic core into the selected one of the plurality of second molds; e) forming an overmold about the plastic core by injecting a material into the mold cavity of the selected one of the plurality of second molds; and f) removing the plastic core and overmold from the mold cavity.
 2. The method of claim 1, further comprising, after Step e), chemically blending the injected material with the plastic core, and cooling the overmold with the chemically blended injected material and the plastic core forming a chemical bond therebetween.
 3. The method of claim 2, wherein the injected material has a temperature that softens the plastic core for chemically blending the core with the injected material.
 4. The method of any one of claims 1, further comprising arranging electrically functional elements within the plastic core, the electrically functional elements including an electrically operated functional unit and an electric supply unit connectable to an energy source for energizing the electrically operated functional unit.
 5. The method of any one of claims 1, wherein Step d) includes enclosing portions of the plastic core within the mold cavity with the plastic core between the enclosed portions.
 6. The method of any one of claims 1, the plastic core including a distal end defining a channel extending into the core, and further comprising inserting electrically functional elements into the channel, and attaching an end cap at the distal end of the plastic core to close the channel.
 7. The method of any one of claims 1, the dental implement including a head member and a neck located between the head member and the plastic core, and further comprising attaching a plurality of bristles to the head member to form a brush head.
 8. The method of any one of claims 1, wherein the injected material is an elastomer.
 9. The method of any one of claim 1, wherein the configurations include one or more of shapes, sizes, colors, patterns, designs and motifs.
 10. A method of manufacturing a dental implement, the dental implement having a shaft with a plastic core, and an overmold, the method comprising: a) providing a first plastic core formed from a first mold; b) selecting a first one of a plurality of second molds, each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second molds and an overmold formed by another one of the plurality of second molds have different configurations; c) placing the first plastic core into the first one of the plurality of second molds; d) forming a first overmold about the first plastic core by injecting a material into the mold cavity of the first one of the plurality of second molds; e) removing the first plastic core and the first overmold from the mold cavity; f) providing a second plastic core formed from the first mold; g) selecting a second one of a plurality of second molds; h) placing the second plastic core into the second one of the plurality of second molds; i) forming a second overmold about the second plastic core by injecting a material into the mold cavity of the second one of the plurality of second molds; and j) removing the second plastic core and the second overmold from the mold cavity.
 11. The method of claim 10, further comprising, after Step d), chemically blending the injected material with the first plastic core, and cooling the first overmold with the chemically blended injected material and the first plastic core forming a chemical bond therebetween; and after Step i), chemically blending the injected material with the second plastic core, and cooling the second overmold with the chemically blended injected material and the second plastic core forming a chemical bond therebetween;
 12. The method of any one of claims 10, wherein the configurations include one or more of shapes, sizes, colors, patterns, designs and motifs.
 13. A dental implement kit, the kit comprising: a first dental implement with a first plastic core formed of a first mold; a first overmold formed of a first one of a plurality of second molds, each of the plurality of second molds having a different mold cavity such that an overmold formed by one of the plurality of the second molds and an overmold formed by another one of the plurality of second molds have different configurations; a second dental implement with a second plastic core formed of the first mold; and a second overmold formed of a second one of a plurality of second molds; wherein the first overmold and the second overmold have different configurations.
 14. The kit of claim 13, wherein the first and second overmolds are formed about the plastic core by injecting a material into the mold cavity of the first and second ones of the plurality of second molds respectively.
 15. The kit of claim 14, wherein the first and second overmolds are formed about the plastic core by chemically blending the injected material with the first and second plastic cores, and cooling the first and second overmolds with the chemically blended injected material and the first and second plastic cores respectively, forming a chemical bond therebetween.
 16. The kit of claim 13, wherein the configurations include one or more of shapes, sizes, colors, patterns, designs and motifs. 